Provided is a solution comprising a polymer and an organic semiconductor compound, wherein the semiconductor compound is a thiophene derivative, and wherein the solvent is a mixture comprising a) at least one of 4-methyl anisole, indane and an alkylbenzene with a linear or branched alkyl group containing from 4 to 7 carbon atoms; and b) at least one of tetrahydronaphthalin and 1,2,4-trimethylbenzene.